#include <iostream>
#include <cmath>

int main()
{
	int a, b, c = 0, ten = 1;
	std::cin >> a >> b;
	for (; a || b; a /= 10, b /= 10)  {
		c += ten * std::abs((a % 10) - (b % 10));
		ten *= 10;
	}
	std::cout << c << '\n';
}

